Registration Form: function prepare() on null - php

Question

I am trying to create a registration form (using an SQL database) that utilizes my
"register.inc.php" file, When I attempt to create an account (as a test) I get
THIS error:
"Fatal error: Call to a member function prepare() on null in /usr/www/world/includes/register.inc.php on line 30"
I've posted the code from my register.inc.php, any insight would be much appreciated.
<?php
include_once 'loginhandler.php';
include_once 'DBclass.php';
$error_msg = "";
if (isset($_POST['username'], $_POST['email'], $_POST['p'])) {
// Sanitize and validate the data passed in
$username = filter_input(INPUT_POST, 'username', FILTER_SANITIZE_STRING);
$email = filter_input(INPUT_POST, 'email', FILTER_SANITIZE_EMAIL);
$email = filter_var($email, FILTER_VALIDATE_EMAIL);
if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
// Not a valid email
$error_msg .= '<p class="error">The email address you entered is not valid</p>';
}
$password = filter_input(INPUT_POST, 'p', FILTER_SANITIZE_STRING);
if (strlen($password) != 128) {
// The hashed pwd should be 128 characters long.
// If it's not, something really odd has happened
$error_msg .= '<p class="error">Invalid password configuration.</p>';
}
// Username validity and password validity have been checked client side.
// This should should be adequate as nobody gains any advantage from
// breaking these rules.
//
$prep_stmt = "SELECT id FROM members WHERE email = ? LIMIT 1";
$stmt = $mysqli->prepare($prep_stmt);
// check existing email
if ($stmt) {
$stmt->bind_param('s', $email);
$stmt->execute();
$stmt->store_result();
if ($stmt->num_rows == 1) {
// A user with this email address already exists
$error_msg .= '<p class="error">A user with this email address already exists.</p>';
$stmt->close();
}
} else {
$error_msg .= '<p class="error">Database error Line 39</p>';
$stmt->close();
}
// check existing username
$prep_stmt = "SELECT id FROM members WHERE username = ? LIMIT 1";
$stmt = $mysqli->prepare($prep_stmt);
if ($stmt) {
$stmt->bind_param('s', $username);
$stmt->execute();
$stmt->store_result();
if ($stmt->num_rows == 1) {
// A user with this username already exists
$error_msg .= '<p class="error">A user with this username already exists</p>';
$stmt->close();
}
} else {
$error_msg .= '<p class="error">Database error line 55</p>';
$stmt->close();
}
// TODO:
// We'll also have to account for the situation where the user doesn't have
// rights to do registration, by checking what type of user is attempting to
// perform the operation.
if (empty($error_msg)) {
// Create hashed password using the password_hash function.
// This function salts it with a random salt and can be verified with
// the password_verify function.
$password = password_hash($password, PASSWORD_BCRYPT);
// Insert the new user into the database
if ($insert_stmt = $mysqli->prepare("INSERT INTO members (username, email, password) VALUES (?, ?, ?)")) {
$insert_stmt->bind_param('sss', $username, $email, $password);
// Execute the prepared query.
if (! $insert_stmt->execute()) {
header('Location: ../error.php?err=Registration failure: INSERT');
}
}
header('Location: ./register_success.php');
}
}
?>

Answer 1

I'm thinking that 'DBclass.php' contains an assignment to "$ mysqli" variable. It's correct? Because in your current script it does not contain any assigment to this variable. (So it's OK, it contains null value because it's never initialized)